In a tubular motor to be used for a purpose, such as winding a curtain-like article; e.g., a shutter, a shading screen, and the like; a motor unit and a planetary gear unit are placed inside a tubular case in an axial direction (refer to Patent Document 1). In the case of a tubular motor illustrated in FIG. 3 of Patent Document 1, a planetary gear unit is placed in a motor unit so as to be directly adjacent, at an output side, to a bulkhead section that supports a rotor, in such a way as to be rotatable, at an output side of the rotor; so that a planetary gear turns while being supported, from a counter-output side, by a flat surface at the output side of the bulkhead section.
Unfortunately, in a configuration illustrated in FIG. 3 of Patent Document 1, there exists no space for collecting grease at a time when the grease, applied to the planetary gear unit, leaks out. Therefore, in the case of a motor illustrated in FIGS. 1A-1C of Patent Document 1, the output side of the bulkhead section is provided with a concave part into which the grease can flow, and moreover a gear cover is placed between the bulkhead section and the planetary gear unit, and then a planetary gear is supported by the gear cover, from the counter-output side. Under such conditions, an outer side part in a radial direction of the gear cover is sandwiched between a cylindrical part where an internal gear is formed in the planetary gear unit and an outer edge part in a radial direction of the bulkhead section.
A brushless motor includes a rotor provided with a rotor magnet, a stator provided with a plurality of drive coils, a magnetic sensor element for detecting a rotation of the rotor magnet, and the like; and in the meantime, a motor current to be supplied to the drive coils is controlled on the basis of a detection result by the magnetic sensor element. In the case where such a brushless motor is used for an electric shutter device and the like, a load of a shutter's own weight, a biasing force of a spring connected to a winding shaft of the shutter, and the like is externally applied to the rotor. Therefore, at a time when the rotor turns in a direction in which the external load is applied, there is a possibility that the rotor turns at a speed higher than a specified speed so that there appears a problem e.g., that the brushless motor gets damaged.
In the meantime, there is proposed a technology for controlling a motor drive operation on the basis of a comparison result between an actual number of revolutions and a specified number of revolutions, while a shutter winding device being provided with a position sensor such as an encoder, and a rotation sensor such as a tacho-generator (refer to Patent Document 2).
In a tubular motor to be used for a purpose, such as winding a curtain-like article; e.g., a shutter, a shading screen, and the like; a motor unit and a planetary gear unit are placed inside a tubular case in an axial direction (refer to Patent Document 1). Such a tubular motor is configured as a motor equipped with a brake, internally having a brake for applying a braking force on a motor shaft, for the purpose of retaining the shutter and the like at a predetermined position (Patent Document 3).
More specifically to describe, in a motor equipped with a brake, described in Patent Document 3; a brake unit includes three brake discs facing one another in a motor shaft direction; and a braking force to be applied to a motor shaft is generated by way of having the three brake discs contacted in the shaft direction. Incidentally, among the three brake discs, a brake disc placed at a center position is provided with a protrusion that protrudes outward in a radial direction from an outer circumferential surface. In the meantime, a groove stretching in the shaft direction is formed on an internal surface of a cylindrical holder that houses the three brake discs, so that locking the protrusion into the groove prevents the brake disc, placed at the center position, from turning around the shaft axis.